The liquid crystal display panel of the liquid crystal display device does not emit light, so that the backlight module is necessarily required to provide the surface light source. The backlight module includes a direct-type backlight module and a side-type backlight module. In a common side-type backlight module, the light emitting diode bar is disposed on the side of the light guide plate, dots are disposed on the light guide plate, and the light provided by the light emitting diode bar is emitted from the light exit surface of the light guide plate by the dots after entering the light guide plate. However, since the light emitting diode light bar is disposed on the side of the light guide plate, some problems such as having uneven luminance may occur and it is not advantageous for local dimming.
In a common direct-type backlight module, a plurality of light emitting diodes arranged as a two-dimensional array are arranged below the diffusion plate. In order to reduce the number of light emitting diodes, a secondary lens corresponding to each of the light emitting diodes is disposed to increase the light emission angle of the light emitting diode. Compared with the side-type backlight module, the direct-type backlight module has better luminance uniformity and is advantageous for local dimming, but has a problem of thicker thickness.
The conventional technology also developed the mix-type backlight module, which mainly use a plurality of light guide plate to replace the secondary lens employed in the direct-type backlight module to reduce the overall thickness of the mix-type backlight module. However, the corners of each of the light guide plates may have obvious dark areas, so that the conventional mix-type backlight module has a problem of uneven luminance.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.